What are the symptoms of vitamin D deficiency?
Yes, deficiency of vitamin D can cause bone pain and muscle weakness. However, mild vitamin D deficiency is not necessarily associated with any symptoms. Vitamin D has been referred to as the "sunlight vitamin" because it is made in our skin when we are exposed to sunlight. It can also be obtained through dietary sources, but the main source of vitamin D in our diet is foods that have been fortified to include the vitamin (such as in milk and other dairy products). Vitamin D is only found naturally in significant levels in a few foods, including fatty fish, cod-liver oil, and eggs.
Vitamin D acts to regulate the calcium and phosphate levels in the body, thus promoting healthy bones. The characteristic vitamin D deficiency state is called rickets. Rickets causes softening and poor mineralization of the bones, leading to skeletal deformities. While rickets is the term typically used to describe the condition in children, osteomalacia refers to the weakening of bones seen in adults who are severely deficient in vitamin D.
The many roles of vitamin D in maintaining health and well-being are a subject of active and ongoing research. Even subclinical (not producing signs or symptoms) deficiencies in vitamin D have been linked to significant health problems. Preliminary studies have shown that in addition to weakening of the bones, vitamin D deficiency may be associated with conditions as varied as cancers, asthma, cardiovascular disease, and autoimmune diseases.
Who is most likely to have vitamin D deficiency?
- Those who have limited sun exposure are at risk for abnormally ow levels of vitamin D, as are people who do not consume dietary sources of vitamin D, particularly in combination with low sun exposure. Human milk and most infant formulas have only very low levels of vitamin D. However, exposure to the sun is not recommended as a source of vitamin D for infants and children due to the long-term risks of skin cancer. The American Academy of Pediatrics recommends vitamin D supplementation starting at 2 months of age for exclusively breastfed infants.
- Some gastrointestinal diseases and condition affect the body's ability to absorb vitamin D from foods. These include gastric bypass surgery, cystic fibrosis, celiac disease, and Crohn's disease.
- People with kidney or liver disease may have lower levels of vitamin D because these organs play a vital role in creating the biologically active form of vitamin D in the body.
- Those with dark skin may have a decreased ability to synthesize vitamin D in response to sunlight. The skin pigment melanin has been shown to inhibit the production of vitamin D by the skin.
- People who are obese (have a BMI of 30 or greater) may have lower levels of vitamin D because fat cells extract vitamin D from the blood.
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How do I know if I have vitamin D deficiency?
Vitamin D deficiency is currently underdiagnosed in the United States. Talk to your health-care professional. If you are at risk of vitamin D deficiency, a simple blood test can determine whether or not vitamin D deficiency is present. This test is not recommended for everyone but is commonly used for people who may have signs of weakened bones or who may have risk factors for vitamin D deficiency.
Can vitamin D deficiency be treated?
Fortunately, vitamin D deficiency is easy to treat with a variety of supplement preparations. Because abnormally high doses of vitamin D can be toxic, it is important to discuss dosages of vitamin D with your health-care professional, who can determine a course of vitamin D supplementation that is best for you.
Medically reviewed by Avrom Simon, MD; Board Certified Preventative Medicine with Subspecialty in Occupational Medicine
Tangpricha, Vin, and Natasha B. Khazai. "Vitamin D Deficiency and Related Disorders." eMedicine.com. Oct. 5, 2009. <http://emedicine.medscape.com/article/128762-overview>.
United States. Office of Dietary Supplements. National Institutes of Health. "Vitamin D." Feb. 25, 2011. <http://ods.od.nih.gov/factsheets/vitamind/>.